It turns out that Kaley Cuoco did not play Penny in the unaired pilot of "The Big Bang Theory," and viewers disliked Katie, the show's initial female lead played by Amanda Walsh.

In 2022, creators Bill Prady and Chuck Lorre discussed the show, with Prady saying, "The female character is kind of rough," and Lorre saying, "Yeah, the audience hated her."

Prady said the hatred stemmed from how she treated two of the show's leads, Sheldon Cooper and Leonard Hofstadter (played by Jim Parsons and Johnny Galecki, respectively).

"We didn't realize early on that the audience viewed them as children. [...] They were very vulnerable, and the audience didn't want a toxic presence around them," Lorre said.

While Sheldon and Leonard

go on to have a sibling-like repertoire with Penny in the early seasons, the character of Katie has a harsh attitude and is quick with cutting insults.

"That's why we rewrote Katie to become Penny and made her much more charmed by the guys and kind to them, as opposed to a woman who would take advantage of them," Lorre said.